Dictionary.com

infectious

[ in-fek-shuhs ]
/ ɪnˈfɛk ʃəs /
Save This Word!

adjective
communicable by infection, as from one person to another or from one part of the body to another: infectious diseases.
causing or communicating infection.
tending to spread from one to another: infectious laughter.
Law. capable of contaminating with illegality; exposing to seizure or forfeiture.
Obsolete. diseased.
QUIZ
ARE YOU A TRUE BLUE CHAMPION OF THESE "BLUE" SYNONYMS?
We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms.
Question 1 of 8
Which of the following words describes “sky blue”?
Meet Grammar CoachWrite or paste your essay, email, or story into Grammar Coach and get grammar helpImprove Your Writing
Meet Grammar CoachImprove Your Writing
Write or paste your essay, email, or story into Grammar Coach and get grammar help

Origin of infectious

First recorded in 1535–45; infect(ion) + -ious

synonym study for infectious

1. See contagious.

OTHER WORDS FROM infectious

WORDS THAT MAY BE CONFUSED WITH infectious

contagious, infectious (see synonym study at contagious)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

How to use infectious in a sentence

British Dictionary definitions for infectious

infectious
/ (ɪnˈfɛkʃəs) /

adjective
(of a disease) capable of being transmittedCompare contagious
(of a disease) caused by microorganisms, such as bacteria, viruses, or protozoa
causing or transmitting infection
tending or apt to spread, as from one person to anotherinfectious mirth
international law
  1. tainting or capable of tainting with illegality
  2. rendering liable to seizure or forfeiture

Derived forms of infectious

infectiously, adverbinfectiousness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for infectious

infectious
[ ĭn-fĕkshəs ]

adj.
Capable of causing infection.
Caused by or capable of being transmitted by infection.
Caused by a pathogenic microorganism or agent.

Other words from infectious

in•fectious•ness n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for infectious

infectious
[ ĭn-fĕkshəs ]

Capable of causing infection. See Note at contagious.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
FEEDBACK